A microfiche appendix, comprising one microfiche, with a total of 24 printed pages of computer program listings, forms part of this specification.
The present invention relates to the embedding of robust identification codes in electronic, optical and physical media, and the subsequent, objective discernment of such codes for identification purposes even after intervening distortion or corruption of the media.
The invention is illustrated with reference to a few exemplary applications, including electronic imagery, emulsion film, and paper currency, but is not so limited.
xe2x80x9cI would never put it in the power of any printer or publisher to suppress or alter a work of mine, by making him master of the copyxe2x80x9d
Thomas Paine, Rights of Man, 1792.
xe2x80x9cThe printer dares not go beyond his licensed copyxe2x80x9d
Milton, Aeropagetica, 1644.
Since time immemorial, unauthorized use and outright piracy of audio and visual source material has caused lost revenues to the owners of such material, and has been a source of confusion and corruption of original work.
With the advent of digitizing data audio signals and images, the technology of copying materials and redistributing them in an unauthorized manner has reached new heights of sophistication, and more importantly, omnipresence. Lacking objective means for comparing an alleged copy of material with the original, owners and possible litigation proceedings are left with a subjective opinion of whether the alleged copy is stolen, or has been used in an unauthorized manner. Furthermore, there is no simple means of tracing a path to an original purchaser of the material, something which can be valuable in tracing where a possible xe2x80x9cleakxe2x80x9d of the material first occurred.
A variety of methods for protecting commercial material have been attempted. One is to scramble signals via an encoding method prior to distribution, and descramble prior to use. This technique, however, requires that both the original and later descrambled signals never leave closed and controlled networks, lest they be intercepted and recorded. Furthermore, this arrangement is of little use in the broad field of mass marketing audio and visual material, where even a few dollars extra cost causes a major reduction in market, and where the signal must eventually be descrambled to be perceived and thus can be easily recorded.
Another class of techniques relies on modification of source audio or video signals to include a subliminal identification signal, which can be sensed by electronic means. Examples of such systems are found in U.S. Pat. No. 4,972,471 and European patent publication EP 441,702, as well as in Komatsu et al, xe2x80x9cAuthentication System Using Concealed Image in Telematics,xe2x80x9d Memoirs of the School of Science and Engineering, Waseda University, No. 52, p. 45-60 (1988) (Komatsu uses the term xe2x80x9cdigital watermarkxe2x80x9d for this technique). An elementary introduction to these methods is found in the article xe2x80x9cDigital Signatures,xe2x80x9d Byte Magazine, November, 1993, p. 309. These techniques have the common characteristic that deterministic signals with well defined patterns and sequences within the source material convey the identification information. For certain applications this is not a drawback. But in general, this is a highly inefficient form of embedding identification information for a variety of reasons: (a) the whole of the source material is not used; (b) deterministic patterns have a higher likelihood of being discovered and removed by a would-be infringer; and (c) the signals are not generally xe2x80x98holographicxe2x80x99 in that identifications may be difficult to make given only sections of the whole. (xe2x80x98Holographicxe2x80x99 is used herein to refer to the property that the identification information is distributed globally throughout the coded signal, and can be fully discerned from an examination of even a fraction of the coded signal. Coding of this type is sometimes termed xe2x80x9cdistributedxe2x80x9d herein.)
What is needed is a reliable and efficient method for performing a positive identification between a copy of an original signal and the original. This method should not only be able to perform positive identification, it should also be able to relate version identification of sold copies in order to better pinpoint the point of sale. The method should not compromise the innate quality of material which is being sold, as does the placement of localized logos on images. The method should be robust so that an identification can be made even after multiple copies have been made and/or compression and decompression of the signal has taken place. The identification method should be largely uneraseable or xe2x80x9cuncrackable.xe2x80x9d The method should be capable of working even on fractional pieces of the original signal, such as a 10 second xe2x80x9criffxe2x80x9d of an audio signal or the xe2x80x9cclipped and pastedxe2x80x9d sub-section of an original image.
The existence of such a method would have profound consequences on audio and image piracy in that it could (a) cost effectively monitor for unauthorized uses of material and perform xe2x80x9cquick checksxe2x80x9d; (b) become a deterrent to unauthorized uses when the method is known to be in use and the consequences well publicized; and (c) provide unequivocal proof of identity, similar to fingerprint identification, in litigation, with potentially more reliability than that of fingerprinting.
In accordance with an exemplary embodiment of the invention, a computer system is provided with associated means for manipulating either digital audio signals or digital images. In cases where original material is in xe2x80x9cnon-digitalxe2x80x9d form, such as on audio tape or on a photograph, means for creating a high fidelity digital copy of the material is included in the illustrative embodiment. This physical system will be referred to as the xe2x80x9cEye-Dxe2x80x9d workstation or system which serves as a concise trade name. The Eye-D system embeds an imperceptible global signal either directly onto the digital original or onto the xe2x80x9cdigitized copyxe2x80x9d of the original if it was in a non-digital form to begin with. The new copy with the embedded signal becomes the material which is sold while the original is secured in a safe place. The new copy will be nearly identical to the original except under the finest of scrutiny; thus, its commercial value will not be compromised. After the new copy has been sold and distributed and potentially distorted by multiple copies, the present disclosure details a method for positively identifying any suspect signal against the original.
It is the use of identification signals which are global (holographic) and which mimic natural noise sources which are two important inter-related features which distinguish the present invention from the collective prior art. This approach allows the maximization of identification signal energy as opposed to merely having it present xe2x80x98somewhere in the original material.xe2x80x99 This allows it to be much more robust in the face of thousands of real world degradation processes and material transformations such as cutting and cropping of imagery.